Date: Wed, 16 Jun 1999 03:25:38 GMT From: "Pierrick Brenot" <cknopsamer.qc.ca> Subject: Re: APC GAUGE
DAVE LEE RALPHSON <davenopsam.freeserve.co.uk> wrote in message news:7k6et4$fuf$1nopsam7.svr.pol.co.uk... > hi gang > can anyone tell me how far the needle on the turbo boost gauge should go. > mine will only go just past the half way or just past the middle of the > yellow section even with my foot to the floor. as I only have had the car 3 > months I don't know what is the norm > car is a 91 9000se auto > > thanks people > Dave Hi Dave (and everybody) Tim Veal responded me as follows, a few weeks ago at the same question : Pierrick, If the needle is entering the red area of the APC guage, there is too much vacuum created by the turbo unit. Now - really this guage is useless and has no bearing on how much Turbo pressure is being created - it measures engine vacuum. However, it's not good to drive it in the red area . . . the wategate actuator rod is not adjusted right - the Bentley manual tells you how to adjust it properly with a vacuum guage (it's a threaded rod). Saab should have put a REAL Turbo guage in their cars - people don't realize that the Turbo/APC guage in the dash isn't really a turbo guage at all, and rely on it as a true reading. Shame on Saab. But, so long as the Overpressure switch is working properly - no serious damage should occur. Your friend Michael may have an overpressure switch that is stuck closed, making it useless and very dangerous to the engine. Bentley tells you how to check it, I think. And no, the wastegate and Turbo overpressure switch are two different things. Best Regards, Tim Veal I have had such "normal boost only" problems during the winter. Two weeks ago, I went to service in my SAAB official dealer (Decarie in Montreal, Qc) and they solved me the problem replacing the APC bypass valve (fig. 18 at page 291-9 on the Bentley's manual), the diaphragm of the valve was leaking closing slowly the valve, I could get some yellow on the indicator at 2/3 max but not full yellow zone. It costed me two hours plus approx ninety canadian dollars. Result is impressive, seems to have 30hp more and a REAL boost on high gears. I can now push the needle easily on the beginning of the red zone but not inside of it. I suppose when exceptional wheather conditions will occur, as -30°C sunny and dry (it happens in Quebec), the needle WILL enter a few seconds the famous red zone. I will tell you if you want. Pierrick Brenot (aka ck) Valleyfield, Quebec, Canada 1991 900T work for Montupet aluminium alloy wheel and heads maker (the SAAB cylinder head maker)
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